1. Technical Field
The present invention relates to a printer having a star wheel to prevent sheet media from lifting up.
2. Related Art
A star wheel having protrusions formed at a regular pitch around the outside is commonly used in printers to prevent sheet media from separating from the platen surface and other parts of the media conveyance path (such as the conveyor belt). JP-A-H04-164766 describes such a printer. The image forming device (printer) described in claim JP-A-H04-164766 has a star wheel rotatably attached to a movable shaft that spans the gap between lever-shaped support brackets. When the top of the device closes, the protrusions on the star wheel contact the paper (media) on the conveyance surface of the paper conveyor belt, and prevent the media from lifting away from the surface.
The conveyance path of the printer opens and closes to remove paper jams or for other maintenance. In a printer that holds media down with a star wheel, the star wheel may be exposed to the space that is opened when the conveyance path is opened. When the star wheel is exposed, the operator's hand or the jammed paper may contact the star wheel, the star wheel may be damaged, and ease of maintenance may drop.
The star wheel in the printer described in JP-A-H04-164766 is covered by the support brackets when the conveyance path is opened. More specifically, the movable shaft on which the star wheel is mounted can move inside a slot formed in the support brackets, and when the top unit is opened, the support brackets descend of their own weight and move to a position below the star wheel. As a result, the star wheel is covered by the support brackets so that it won't be touched by the operator's hand.
The construction described in JP-A-H04-164766, however, requires a member (the support brackets) to cover the star wheel to prevent exposing the star wheel, the parts count therefore increases, and construction is complicated.
The present invention provides a printer with a simple configuration that prevents a star wheel used to prevent media from lifting up from being exposed to the conveyance path when the conveyance path is opened.